The present invention is related generally to satellite communication systems. More particularly, the present invention is related to an assembly for combining communication signals within a beamforming architecture of a multi-beam phased array antenna.
Multi-beam antennas are used in a variety of communication applications, such as on satellites. Current multi-beam antennas are divided into two classes, the fixed spot beam type and the multi-beam phased array type. The fixed spot beam type antennas require additional design investment, such as in componentry and system control, to provide beam pointing and shape altering capability. The multi-beam phased array type antennas can be electronically reconfigured without such design investment, but are commonly formed in a “brick” type architecture. The brick architecture has significant height and a substantial amount of components.
Phase array antennas typically include multiple radiating elements, element and signal control circuits, a signal distribution network, a power supply, and a mechanical support structure. Integration of these components can be time consuming and interconnections contained therein can degrade reliability of an antenna. Also, due to limited space on a satellite, there is a limited amount of area on the non-signal transmission side of the radiating element of the antenna for the above stated circuitry and structures.
A multi-beam phased array antenna often has multiple RF inputs, which are referred to as elements. For aperture efficiency and reuse, each element has a single input antenna to capture or radiate RF energy followed by an amplifier. For multi-beam applications, the received input signal is divided into N signals that correspond to an N number of resulting beams after amplification. After division, a beamformer applies amplitude and phase weighting to each channel of each element. For an array of M elements and N beams, there are M×N weighting circuits or beamforming paths. The signal energy from each beam and each element is combined in a power combiner, which has an N number of layers. For M elements and N beams, a quantity of N, M-to-one combiners are required.
Packaging radio frequency (RF) beamforming circuitry for multiple beams in the available space on the non-signal side of the radiating elements can require configuring the circuitry and structures in a vertical fashion. This vertical arrangement increases height of the antenna.
Also, the use of a vertical arrangement results in the use of separate modules for each of the beamforming circuits with many interconnections between the modules and power combining circuitry. The interconnections can negatively affect reliability and correspond to an increase in associated components. The interconnections and the associated costs involved therein increase costs in an antenna and increase componentry integration time. The physical size of the antenna also limits the mounting locations for the antenna.
Thus, there exists a need for an improved multiple phased array antenna having an electrical coupling and packaging configuration that minimizes antenna size, the number of interconnections, component and manufacturing costs, and integration time.